I wonder how pervasive this actually is. I've worked a bit in retail technology and we put some sensors in live stores. Tracking dwell time and pings of wifi access points. They generated a ton of noise and almost zero actionable data. Every attempt failed to be deployed to a second store. We had some success with facial recognition but only in really funneled spaces where we could get a customer to look at a camera on purpose. And it was still only about 90% accurate.